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  Subjects -> CHEMISTRY (Total: 882 journals)
    - ANALYTICAL CHEMISTRY (54 journals)
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ANALYTICAL CHEMISTRY (54 journals)

Showing 1 - 54 of 54 Journals sorted alphabetically
Accounts of Chemical Research     Full-text available via subscription   (Followers: 125)
Acta Analytica     Hybrid Journal   (Followers: 7)
Advances in Analytical Chemistry     Open Access   (Followers: 31)
American Journal of Analytical Chemistry     Open Access   (Followers: 33)
Analytica Chimica Acta     Hybrid Journal   (Followers: 39)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 32)
Analytical and Bioanalytical Chemistry Research     Open Access   (Followers: 1)
Analytical Chemistry     Full-text available via subscription   (Followers: 267)
Analytical Chemistry Insights     Open Access   (Followers: 24)
Analytical Chemistry Letters     Hybrid Journal  
Analytical Chemistry Research     Open Access   (Followers: 10)
Analytical Letters     Hybrid Journal   (Followers: 10)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 10)
Biomonitoring     Open Access   (Followers: 2)
Chemical Data Collections     Hybrid Journal  
Chinese Journal of Analytical Chemistry     Full-text available via subscription   (Followers: 4)
Combinatorial Chemistry - an Online Journal     Open Access   (Followers: 3)
Composites Communications     Full-text available via subscription   (Followers: 2)
Comprehensive Analytical Chemistry     Full-text available via subscription   (Followers: 6)
Critical Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 27)
Current Analytical Chemistry     Hybrid Journal   (Followers: 9)
Drug Testing and Analysis     Hybrid Journal   (Followers: 9)
Electroanalysis     Hybrid Journal   (Followers: 8)
Field Analytical Chemistry and Technology     Hybrid Journal   (Followers: 5)
Handbook of Analytical Separations     Full-text available via subscription   (Followers: 3)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription   (Followers: 1)
International Journal of Analytical Chemistry     Open Access   (Followers: 20)
International Journal of Chemical and Analytical Science     Full-text available via subscription   (Followers: 3)
International Journal of Environmental Analytical Chemistry     Hybrid Journal   (Followers: 6)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 8)
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 7)
Journal of Analytical Atomic Spectrometry     Full-text available via subscription   (Followers: 13)
Journal of Analytical Chemistry     Hybrid Journal   (Followers: 24)
Journal of Combinatorial Chemistry     Full-text available via subscription   (Followers: 1)
Journal of Electroanalytical Chemistry     Hybrid Journal   (Followers: 6)
Journal of Electroanalytical Chemistry and Interfacial Electrochemistry     Full-text available via subscription   (Followers: 1)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 2)
Journal of Radioanalytical and Nuclear Chemistry     Hybrid Journal   (Followers: 8)
Journal of Thermal Analysis and Calorimetry     Hybrid Journal   (Followers: 24)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 2)
Microchemical Journal     Hybrid Journal   (Followers: 4)
Nature Catalysis     Hybrid Journal  
Nigerian Journal of Chemical Research     Full-text available via subscription   (Followers: 2)
Phytochemical Analysis     Hybrid Journal   (Followers: 3)
Polish Journal of Chemical Technology     Open Access   (Followers: 2)
Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 10)
Sample Preparation     Open Access   (Followers: 1)
Surface and Interface Analysis     Hybrid Journal   (Followers: 16)
Techniques and Instrumentation in Analytical Chemistry     Full-text available via subscription   (Followers: 5)
TrAC Trends in Analytical Chemistry     Full-text available via subscription   (Followers: 55)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 3)
Vibrational Spectroscopy     Hybrid Journal   (Followers: 12)
World Journal of Analytical Chemistry     Open Access   (Followers: 2)
Journal Cover Journal of Analytical Chemistry
  [SJR: 0.268]   [H-I: 23]   [24 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1608-3199 - ISSN (Online) 1061-9348
   Published by Springer-Verlag Homepage  [2350 journals]
  • Chromatographic Determination of Lignans (Antioxidants) in Food Products
    • Authors: A. Ya. Yashin; D. B. Yashunskii; A. N. Vedenin; N. E. Nifant’ev; B. V. Nemzer; Ya. I. Yashin
      Pages: 399 - 406
      Abstract: Interest in lignans is continually growing in recent years because of their strong antioxidant properties and other biological characteristics, positively affecting human health. Methods for the extraction, identification, and determination of lignans are developed; lignan species and their quantity in food products are determined, and databases of lignans in food products have been created in several countries (Finland, Netherlands, United States, Canada, United Kingdom, Japan, and Spain). In this review, we consider chromatographic methods (gas, liquid, supercritical fluid, and thin-layer chromatography) used to identify and determine natural lignans and isolate them in an individual state. Most natural lignans are found in flax and sesame seeds, cereals, some vegetables, fruits, and berries.
      PubDate: 2018-05-01
      DOI: 10.1134/s106193481805012x
      Issue No: Vol. 73, No. 5 (2018)
       
  • Two-Laser Thermal Lens Spectrometry with Signal Back-Synchronization
    • Authors: D. A. Ivshukov; I. V. Mikheev; D. S. Volkov; A. S. Korotkov; M. A. Proskurnin
      Pages: 407 - 426
      Abstract: A two-laser dual-beam thermal lens spectrometer based on continuous-wave lasers, which implements the mode with signal back-synchronization, is developed with the aim to develop instrumentation for thermal lens spectrometry. This mode offers a potentially higher sensitivity of measurements in comparison with the lock-in mode of thermal lens measurements and variation of conditions depending on the measurement medium (solvent, or dispersed system, or solids). The wider possibilities of the back-synchronization mode in thermal lens spectrometry both for solving problems of chemical analysis and in some related fields are shown.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050076
      Issue No: Vol. 73, No. 5 (2018)
       
  • Extraction of Metals in a Water‒Potassium
           Bis(Alkylpolyoxyethylene)Phosphate‒Ammonium Sulfate System with Various
           Photometric Reagents
    • Authors: S. A. Denisova; A. E. Lesnov; N. N. Ostanina
      Pages: 427 - 431
      Abstract: The interfacial distribution of a number of organic photometric reagents in a water‒potassium bis(alkylpolyoxyethylene)phosphate (oxyphos B)‒ammonium sulphate splitting system is studied. It is found that alizarin complexone, 1-(2-pyridylazo)-2-naphthol-2 (PAN), bromothymol blue, rhodamine 6G, pyrogallol red, morin, fuchsine, malachite green, bromothymol blue, pyrocatechol violet (PCV), chromazurol S, and aluminon are extracted with partition coefficients higher than 100. A possibility of the extraction‒photometric determination of gallium with PCV and cobalt with PAN is shown. The proposed procedures do not require the use of fire-hazardous, volatile, and toxic organic solvents.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818030048
      Issue No: Vol. 73, No. 5 (2018)
       
  • Selection of Conditions for Chromatomembrane Gas Extraction at Its
           Combination with the Gas-Adsorption Preconcentration of Analytes
    • Authors: O. V. Rodinkov; A. S. Bugaichenko; L. N. Moskvin; A. R. Gorbacheva; E. A. Vagner
      Pages: 432 - 437
      Abstract: Optimal conditions (temperature, porous structure and configuration of mass exchange layer in the chromatomembrane cell, and also the direction of water sample and extractant gas flows through it) for the chromatomembrane gas extraction of volatile organic compounds from aqueous solutions in combination with the gas-adsorption preconcentration of the analytes are selected. An analysis scheme based on a combination of these methods and a two-step thermal desorption of analytes ensures the shortening of the preconcentration time by several times compared to the schemes involving traditional bubbling. Metrological characteristics are given and the accuracy of the developed scheme of analysis is proved.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050106
      Issue No: Vol. 73, No. 5 (2018)
       
  • 2-Nitrobenzaldehyde Thiocarbohydrazone Assisted Precise Extraction
           Spectrophotometric Method for the Determination of Ruthenium(III) in Alloy
           and Catalysts
    • Authors: Sunil B. Zanje; Vishal J. Suryavanshi; Arjun N. Kokare; Anita A. Ghare; Ganesh S. Kamble; Pravin N. Kamble; Mansing A. Anuse
      Pages: 438 - 451
      Abstract: A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)‒2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1‒6 g/mL of ruthenium(III), the optimum concentration range was 2‒5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 104 L/mol/cm and 0.0075 μg/cm2, respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050131
      Issue No: Vol. 73, No. 5 (2018)
       
  • Separation, Preconcentration and Spectrophotometric Determination of
           Rhodamine B in Industrial, Cosmetic and Water Samples by Cloud Point and
           Solid Phase Extraction
    • Authors: A. T. Bişgin; Y. Sürme; M. Uçan; İ. Narin
      Pages: 452 - 458
      Abstract: The aim of this study is extraction, preconcentration and spectrophotometric determination of Rhodamine B (RB) in aqueous media by developing solid phase extraction (SPE) and cloud point extraction (CPE) methods. Amberlite XAD-1180 adsorbent and Tergitol NP-7 surfactant were used for SPE and CPE, respectively. Parameters of SPE and CPE which effected quantitative extractions were investigated and optimized. Matrix effects of some ions and dyes were analyzed at the optimum conditions. Developed methods were used to determine RB contents of anti-freeze, lipstick and water samples. The results of both methods demonstrated that the RB was quantitatively extracted and determined. RB contents of solid samples were found between 473 ± 15 and 317 ± 8 μg/g; 472 ± 11 and 312 ± 6 μg/L dye contents were determined for liquid samples. The methods were tested by analysis of spiked samples. Analytical characteristics of the methods were compared with each other and previously reported studies.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050040
      Issue No: Vol. 73, No. 5 (2018)
       
  • Spectrophotometric and Titrimetric Assay of Flutamide in Pharmaceuticals
    • Authors: K. Basavaiah; N. Rajendraprasad
      Pages: 459 - 464
      Abstract: Three methods, two spectrophotometric and one titrimetric, which are simple, easy to perform and cost-effective, are presented for the determination of flutamide, an anti-cancer drug. In the first spectrophotometric method (method A), absorbance of flutamide solution in methanol was measured at 290 nm. Measurement of absorbance of reduced flutamide (RFAD) in HCl at 245 nm serves as the basis of the second spectrophotometric method (method B). RFAD, in strong HCl medium was titrated vs standard sodium nitrite, determining the end-point potentiometrically (method C). Experimental variables influencing assays were studied and optimized. Beer’s law was obeyed over concentration ranges: 2.5–25.0 and 1.0–9.0 μg/mL for method A and method B, respectively, with molar absorptivity values of 1.0 × 104 and 2.4 × 104 L/(mol cm). Calculated limits of detection and quantification were 0.18 and 0.54 μg/mL (method A) and 0.16 and 0.18 μg/mL (method B). Titration reaction followed a 1: 1 stoichiometry and the method is applicable to 4‒30 mg RFAD. Repeatability, reproducibility and accuracy of the methods were satisfactory. The methods were also validated for selectivity, robustness and ruggedness. The developed methods were applied to the determination of active ingredient in tablets, and the results agreed well with the label claim and those of a reference method. Accuracy was also assessed by recovery test via standard–addition procedure. The drug was subjected to different stress conditions, such as acid and base hydrolysis, oxidation and thermolysis and analyzed subsequently by method A, as a part of stress testing. Results indicated that the drug is slightly vulnerable to all stress-conditions studied.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050039
      Issue No: Vol. 73, No. 5 (2018)
       
  • Sols of Silver Nanoparticles as Analytical Reagents for the Determination
           of Active Chlorine in Water Samples by Spectrophotometry and Photometric
           Titration
    • Authors: A. Yu. Olenin; E. G. Olenina
      Pages: 465 - 469
      Abstract: Sols of silver nanoparticles surface-stabilized by cetyltrimethylammonium bromide or polyvinylpyrrolidone can be used for the determination of active chlorine in water samples. As analytes modeling active chlorine in water, we used freshly prepared sodium hypochlorite solutions. Because of the high values of standard electrode potentials of reduction half-reactions, active forms of chlorine can oxidize silver nanoparticles, exhibiting the effect of surface plazmon resonance with an absorption maximum near 400 nm. The absorption intensity of silver nanoparticles correlates with the concentration of sodium hypochlorite. This effect was used for the qualitative and quantitative determination of active chlorine in water samples. The quantitative characteristics of the described method were obtained for two versions of analysis, spectrophotometry and photometric titration. The calibration graphs for both versions were similar and linear in the range of sodium hypochlorite concentrations 0.1–2.5 mM.
      PubDate: 2018-05-01
      DOI: 10.1134/s106193481805009x
      Issue No: Vol. 73, No. 5 (2018)
       
  • MnO 2 /3MgO Nanocomposite for Preconcentration and Determination of Trace
           
    • Authors: Gholamreza Khayatian; Marzieh Moradi; Shahed Hassanpoor
      Pages: 470 - 478
      Abstract: The presented study investigates the application of MnO2/3MgO nanocomposite, as a new sorbent for solid phase extraction and determination of trace amounts of Pb2+ and Cu2+ from various samples using flame atomic absorption spectrometry. After extraction, the analytes were desorbed using 0.01 M ethylenediaminetetraacetic acid. The effects of various parameters were studied and optimized. Under optimized experimental conditions the linear dynamic ranges for Cu2+ and Pb2+ were 10‒900 and 30‒900 μg/L, respectively, with a preconcentration factor of 20. The detection limits of Cu2+ and Pb2+ were 4 and 11 μg/L, respectively, and relative standard deviations for eight determinations of 100 μg/L were 3.6 and 3.8% for Cu2+ and Pb2+, respectively. The method was successfully applied for determination of copper and lead in mushrooms, rice, tap water and refinery wastewater with good spike recoveries ranging between 95‒106%.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050088
      Issue No: Vol. 73, No. 5 (2018)
       
  • Determination of Sulfur in Geological Samples and Soils Using a
           High-Temperature Arc Plasmatron
    • Authors: D. A. Tyurin; E. G. Sil’kis; E. N. Savinova
      Pages: 479 - 485
      Abstract: We developed a procedure and determined the concentration of sulfur in different geological samples and soils on a special-purpose emission spectrometer using a high-temperature arc plasmatron in the concentration range from 10 to 20000 ppm.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050118
      Issue No: Vol. 73, No. 5 (2018)
       
  • A Distribution Chromatography Method for the Identification of Pesticides
           in Their Mixtures and Agricultural Products
    • Authors: M. F. Zayats; S. M. Leschev
      Pages: 486 - 496
      Abstract: The distribution of 166 pesticides of various classes (amides, dinitroanilines, pyrethroids, thiocarbamates, triazines, etc.) was studied at 20 ± 1°C in multiple extraction systems. The distribution constants (P) of pesticides between hexane and a polar phase are calculated. Based on the distribution constants of pesticides, a possibility of using distribution chromatography for their identification was considered. It is demonstrated on an example of pesticides with similar retention times that the hexane–water extraction system is most selective and universal for the identification of most compounds by gas and liquid chromatography. Using this system, logarithms of distribution constants of the substances under consideration are maximally differentiated and ranged from–1.32 to 8.0. Such a range makes it possible, with an acceptable volume ratio of the hexane and water phases (up to 1: 500), to achieve a significant decrease in the peak area of the pesticide in hexane when it is washed with water in accordance with its P value up to logP = 3.0. In the case of more hydrophobic pesticides, extraction systems of hexane–ethylene glycol, hexane–acetonitrile, and hexane–mixtures of acetonitrile with water and ethylene glycol can be used.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050143
      Issue No: Vol. 73, No. 5 (2018)
       
  • Simultaneous Determination of Hydrazine, Methylhydrazine, and
           1,1-Dimethylhydrazine by High-Performance Liquid Chromatography with Pre-
           and Post-Column Derivatization by 5-Nitro-2-Furaldehyde
    • Authors: A. S. Amosov; N. V. Ul’yanovskii; D. S. Kosyakov; O. A. Shpigun
      Pages: 497 - 503
      Abstract: Approaches to the chromatographic determination of 1,1-dimethylhydrazine and two main products of its degradation (hydrazine and methylhydrazine) on their simultaneous presence are proposed using derivatization by 5-nitro-2-furaldehyde and multi-wavelength spectrophotometric detection of the formed derivatives in the visible spectral region. A combination of preliminary derivatization with separation in the reversed-phase HPLC mode and also ion-chromatographic separation with post-column derivatization allowed us to reach the limits of detection for analytes lower than 1 μg/L and to determine 1,1-dimethylhydrazine at the level of the maximum permissible concentration without preconcentration. The developed approaches were tested on an acid extract of a sample of peat bog soil collected at the place of impact of the first stage of a carrier rocket. The identity of the results obtained by different methods and the high level of soil pollution by hydrazines are shown.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050027
      Issue No: Vol. 73, No. 5 (2018)
       
  • Determination of Rutin in Drinks Using an Electrode Modified with Carbon
           Nanotubes-Prussian Blue
    • Authors: Edgar Nagles; Johisner Penagos-Llanos; Olimpo García-Beltrán; John Hurtado
      Pages: 504 - 511
      Abstract: A new sensor was developed using a screen-printed carbon electrode modified with single-walled carbon nanotubes (SWCNTs) and Prussian blue (PB) coated with chitosan. The modified electrode allowed the oxidation and reduction of rutin at 0.25 and 0.096 V, respectively, with a ΔE of 0.154 V. Furthermore, the peak currents increase nearly 100% compared with the electrode without modification. The process was more reversible compared with the electrode modified with only SWCNTs or PB. Cyclic voltammetry was used to characterize the modified electrode surface. The quantification of rutin was more sensitive with adsorptive stripping voltammetry than with anodic stripping voltammetry. Adsorption potential, adsorption time and pH were optimized based on the oxidation of rutin: Eads =–0.10 V, tads = 60 s, pH 3.0. The detection limit (3σ/b) was 0.01 μM and the relative standard derivation was 3%. The new sensor was used in the quantification of rutin in black tea, coffee and synthetic drink of tea with satisfactory results.
      PubDate: 2018-05-01
      DOI: 10.1134/s1061934818050064
      Issue No: Vol. 73, No. 5 (2018)
       
  • Methods of Determination of Antibiotic Residues in Honey
    • Authors: S. M. Jakšić; R. D. Ratajac; N. B. Prica; J. B. Apić; D. B. Ljubojević; M. Z. Žekić Stošić; M. M. Živkov Baloš
      Pages: 317 - 324
      Abstract: Monitoring antibiotics residues in honey and honey products helps to assess the potential risk of these products to human health. These data provide an insight in the extent of antibiotic treatment that has been used during the beekeeping and enable the evaluation of potential environment pollution with antibiotic residues. This article offers an overview of methods for identification and determination of different antibiotics potentially present in honey, as well as of maximum residue limits for antibiotics in bee products, in particular honey. It is important to stress the importance of strict monitoring system and validation of analytical methods that will enable an accurate, precise and reliable determination of acceptable minimal concentrations of pollutants in honey.
      PubDate: 2018-04-01
      DOI: 10.1134/s1061934818040044
      Issue No: Vol. 73, No. 4 (2018)
       
  • Application of Silica Chemically Modified by Sulfur-Containing Groups to
           the Separation and Determination of Platinum and Rhenium in Catalysts
           Based on Aluminum Oxide
    • Authors: V. N. Losev; V. V. Parfenova; E. V. Elsuf’ev; O. V. Buiko; S. L. Didukh; O. V. Belousov; N. G. Maksimov
      Pages: 325 - 333
      Abstract: Adsorbents based on silica chemically modified by sulfur-containing groups (dithiocarbamate, thiodiazolethiol, mercaptophenyl, and aminobenzothiazole) quantitatively extract (recovery ≥99%) platinum( IV) from solutions ranging from 4 M HCl to pH 6. Under the conditions of the adsorption separation of platinum(IV), rhenium(VII) is not extracted and remains in the solution. The subsequent quantitative (98–99%) adsorption of rhenium(VII) is achieved in the presence of a 1000-fold excess of tin(II) chloride. Adsorption on the surface of adsorbents leads to the formation of platinum(II) complexes with sulfur-containing groups, luminescent at 77 K on irradiation with UV light. The luminescence spectra of surface platinum( II) complexes are located in the region of 550–700 nm. In the adsorption of rhenium(III) in the presence of tin(II) chloride, intensely colored brown complexes of rhenium formed on the surface of adsorbents. Electron paramagnetic resonance showed that, in the surface complexes, rhenium is in the oxidation state 2+. Silicas chemically modified by sulfur-containing groups were used in the development of procedures for the sequential isolation and determination of platinum and rhenium in solutions after the decomposition of aluminum–platinum–rhenium catalysts.
      PubDate: 2018-04-01
      DOI: 10.1134/s106193481804007x
      Issue No: Vol. 73, No. 4 (2018)
       
  • Characterization of Refuse Derived Fuel Using Thermogravimetric Analysis
           and Chemometric Techniques
    • Authors: Panagiotis Danias; Stylianos Liodakis
      Pages: 351 - 357
      Abstract: An approach for characterization of refuse derived fuel (RDF) using thermogravimetry and chemometric techniques was developed. For this purpose, a series of samples coming from lignocellulosic products (wood, cardboard, paper, newspaper) and plastics (polyethyleneterephthalate, high density polyethylene, polypropylene, polypropylene, nylon and polyvinylchloride), as well as their mixtures, were investigated by means of thermogravimetry (TG) in a temperature range between 25 and 800°C. The datapoints of TG diagrams (weight loss) were then subjected to principal component analysis in order to unravel similarities/ dissimilarities of the investigated samples. A classification was obtained according to their woody/petroleum derived origination. This classification was more evident if partial least square discriminant analysis was employed. Finally, a partial least square analysis was carried out for the determination of lignocellulosic content in the sample. The model was validated by application to samples with known mass fraction of lignocellulosic products. Finally, the model was applied to two RDF samples using fractions of their particle sizes from 1 mm to less than 0.032 mm, and the results were compared with their ultimate and proximate analysis.
      PubDate: 2018-04-01
      DOI: 10.1134/s106193481804010x
      Issue No: Vol. 73, No. 4 (2018)
       
  • Analysis of Niobium–Rare-Earth Ores by Inductively Coupled Plasma
           Mass Spectrometry
    • Authors: V. K. Karandashev; A. M. Zybinsky; V. P. Kolotov; S. V. Kordyukov; V. A. Simakov; T. V. Orlova
      Pages: 364 - 373
      Abstract: To determine the composition of niobium–rare-earth ores by atomic emission spectrometry and inductively coupled plasma mass spectrometry, two procedures are developed for sample preparation based on autoclave decomposition and flux fusion. Autoclave decomposition is carried out in a mixture of HF and HNO3 at a temperature of up to 220°C and a pressure of up to 160 atm using a developed system with resistive heating. Subsequent evaporation to dry salts ensures the removal of F– ions and silicon as SiF4. The residue is dissolved in a mixture of HCl and H2O2 at 160°C under elevated pressure. The resulting solutions (10% with respect to HCl with the addition of H2O2) are diluted before measurements. The dissolution process is monitored for each sample using stable highly enriched isotopes of 91Zr, 100Mo, 149Sm, and 178Hf. The second procedure is based on fusing samples with a mixture of Na2CO3 and Na2B4O7 at 1050°C in a muffle furnace and dissolving the resulting melt in a mixture of HCl and H2O2. The procedures were tested using the national (NFS-23) and foreign standard samples of composition (OREAS-462, 463, 464, 465, Australia) and real samples of niobium–rare-earth ores.
      PubDate: 2018-04-01
      DOI: 10.1134/s1061934818040056
      Issue No: Vol. 73, No. 4 (2018)
       
  • Effect of the Nature of a Quaternary Ammonium Salt and the Addition of a
           Neutral Carrier on Analytical Characteristics of Sulfate-Selective
           Electrodes
    • Authors: Yu. V. Matveichuk; E. M. Rakhman’ko; E. B. Okaev
      Pages: 374 - 382
      Abstract: A film polyvinyl chloride sulfate-selective electrode based on the sterically accessible higher quaternary ammonium salt, 3,4,5-tris(dodecyloxy)benzyl(oxyethyl)3trimethylammonium chloride, using 1-bromonapthalene as a plasticizer and heptyl p-trifluoroacetylbenzoate as a solvating agent was developed. The limit of detection of the electrode was 6.7 × 10−7 M, lifetime was 1 month, and the slope of the electrode function was 27 mV/decade. The electrode is selective in the presence of interfering Cl−, C2O4−, Br−, and NO3−ions. The interference of carbonate ions was eliminated by maintaining pH at 3.2 ± 0.1. Based on IR spectroscopic and potentiometric studies, it is most likely that the solvation of sulfate ions with heptyl p-trifluoroacetylbenzoate occurs through interaction with the trifluoroacetyl carbonyl carbon atom rather than with hydroxyl groups of the hydrate form.
      PubDate: 2018-04-01
      DOI: 10.1134/s1061934818040081
      Issue No: Vol. 73, No. 4 (2018)
       
  • Single-Walled Carbon Nanotubes Functionalized with N-(6-aminohexyl)
           Carboxamide as Ionophore for Sensing Silver Ions
    • Authors: K. Mehdizadeh; M. Giahi; H. Aghaie
      Pages: 383 - 389
      Abstract: In this work; we constructed a silver ion-selective electrode based on N-(6-aminohexyl) carboxamide functionalized single-walled carbon nanotubes (NAHAFSWCN) as an ionophore. The selectivity constant of a number of cations was measured using silver ion selective electrode. Optimal pH was between 3 and 6 and the upper and lower detection limits of the designed electrode were 1.2 × 10–2 and 8 × 10–7 M. The electrode showed a Nernstian response over a silver ion concentration range of 1 × 10–6 to 1 × 10–2 M with a slope of 59.1 ± 0.5 mV/decade. The response time of the electrode was less than 18 s and its effective lifetime was 3 months. The isothermal temperature coefficient of the electrode dE°/dT was determined as 0.00011 V/grad. Thermodynamic functions such as ΔS°, ΔH° and ΔG° were obtained by calculating the thermal coefficient of the electrode.
      PubDate: 2018-04-01
      DOI: 10.1134/s1061934818040093
      Issue No: Vol. 73, No. 4 (2018)
       
  • Selective Voltammetric and Flow-Injection Determination of Guanosine and
           Adenosine at a Glassy Carbon Electrode Modified with a Ruthenium
           Hexachlororuthenate Film
    • Authors: L. G. Shaidarova; A. V. Gedmina; V. D. Demina; I. A. Chelnokova; H. C. Budnikov
      Pages: 390 - 398
      Abstract: An inorganic film of ruthenium hexachlororuthenate (RuRuCl6), deposited on the surface of a glassy carbon electrode, exhibits electrocatalytic activity in the oxidation of purine nucleosides, such as guanosine and adenosine. Appropriate operating conditions are found for fabricating a polymer film on the surface of glassy carbon and for recording the maximum electrocatalytic current for the modified electrode. A method for the selective voltammetric determination of guanosine and adenosine in their simultaneous presence at an electrode modified by a RuRuCl6 film is developed. A procedure is proposed for the amperometric detection of purine nucleosides with this modified electrode under the conditions of flow-injection analysis. The linear dependence of the analytical signal on the concentration of guanosine and adenosine is observed up to 5 × 10–6 M in the stationary mode and up to 5 × 10–7 M in the flow system. The proposed method for the selective determination of guanosine and adenosine was tested in the analysis of human urine.
      PubDate: 2018-04-01
      DOI: 10.1134/s1061934818040111
      Issue No: Vol. 73, No. 4 (2018)
       
 
 
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